awk to insert line previous to a pattern?

I have a very long line with certain patters embedded in there. I need to be able to read that line, and when it encounters that pattern, create a new line.

I want the pattern to be the beginning of the new line.

I thought sed or awk could do this, but everything I try in sed gives me a "sed garbled" message.

Any thoughts?

awk '{gsub("pattern", RS "pattern")}1' file

sed 's/pattern/\
&/g' file